In our earlier patent application, PCT Patent Publication No. WO 98/53761 entitled “A prosthesis and a method deploying a prosthesis” there is disclosed an introducer for a stent graft which retains the stent graft so that each end can be moved independently during the process of endovascular deployment of the stent graft. This device requires that a number of actions be taken in a particular consecutive order to place a stent graft in the required position in the vasculature and then release one end of the stent graft and then another end and if required, between the release of each of the ends, the placement of a branch stent graft from a side arm of the stent graft. These features and other features disclosed in PCT Patent Publication No. WO 98/53761 are incorporated herewith in their entirety into this specification.
It is desirable that the set of sequential actions necessary to release the stent graft at the desired position in the vasculature be undertaken in the required order and that there be less chance for operator error during such a deployment.
It has been found, however, that a stent graft which includes self expanding stents engaging against the inner surface of the sheath, trigger wires retaining the graft onto the pusher as well as the general friction of interacting components can provide significant load. It is the intention of this invention to provide a system to assist with the withdrawing of a sliding portion into the handle of a delivery device.
It is the object of this invention therefore to provide a deployment device which is arranged to introduce, deploy and release a stent graft by a series of sequential actions.
Throughout this specification the term distal with respect to a portion of the aorta, a deployment device or a prosthesis means the end of the aorta, deployment device or prosthesis further away in the direction of blood flow away from the heart and the term proximal means the portion of the aorta, deployment device or end of the prosthesis nearer to the heart. When applied to other vessels similar terms such as caudal and cranial should be understood.
The invention will in general be discussed in relation to deployment of a stent graft into the abdominal aorta but the invention is not so limited and can apply to deployment into other portions of the aorta or into other vessels of the human or animal body.
Throughout this discussion the term “stent graft” is intended to mean a device which has a tubular body of biocompatible graft material and at least one stent fastened to the tubular body to define a lumen through the stent graft. The stent graft may be bifurcated and have fenestrations, side arms or the like. Other arrangements of stent grafts are also within the scope of the invention.